Hydrocarbon recovery factor is defined as the ratio of producible hydrocarbon to in situ hydrocarbon, namely the original hydrocarbon in place. Determining the amount of in situ hydrocarbon is key to the economic assessment of hydrocarbon production at a particular location, and also dictates the production methods to be utilized there. One of the attributes of characterizing the reservoir quality and hydrocarbon quantity is irreducible water saturation (Swir); the water saturation resulting from the balance between capillary pressure that holds on to the water and gravitational force that drains the water downward. For good quality rock, the value of irreducible water saturation is usually very low if it is high above the free water level, but still can be reduced lower if the rock with the irreducible water could be moved higher from its original place, i.e., by increasing gravitational driving forces. Thus, “irreducible” water saturation can, theoretically, be reduced if the balance between the draining force and binding force is disrupted, by either increasing gravitational draining force or reducing capillary binding force. For core samples taken from an oil column in a reservoir with oil-based coring fluid, the water saturation measured from a core sample with good rock quality is usually very low, depending on the type of rock and the location of the core sample with respect to the free water level. This very low water saturation is referred to as irreducible water saturation in this disclosure. In terms of water property, this irreducible water is most likely connate water, water trapped in the pores space during formation of the rock. Another source is interstitial water (Swi), which is generally defined as water that occurs naturally within the rock pore space. Part of this irreducible water saturation may be recovered by using centrifuge or core-flood techniques. These techniques involve flowing oil or gas through a preserved native state core samples taken from the oil column, or spinning it in a centrifuge to displace the water with oil or gas. These techniques often result in recovery of some of the water, but the core samples are often destructed, depending on their mechanical strength, and thus, the success rate is low. It is very challenging and expensive to obtain consistent results.